NEW KARORI TUNNEL PROPOSAL 2020 © Copyright Karori Residents’ Association Author Bill Guest 10 September 2020 © Copyright Karori Residents’ Association – Author Bill Guest 10 September 2020 EMBARGOED AGAINST ANY DELIVERY UNTIL 11am 24 NOVEMBER 2020 Suggested new tunnel route William (Bill) Guest Bill is a retired civil engineer who has lived in Karori for 26 years. He graduated with a B.E. (Civil) from the University of Canterbury in 1968, and later earned an M.E. (Civil) (First Class) from the University of Auckland in 1976. This postgraduate degree was focussed on transportation engineering. He later completed Diplomas in Business Administration and in Business Computing from Massey University. Bill spent most of his career in transport, much of it in or associated with railways, including senior management roles. The last seven years of his career were with Veolia Transport (now Transdev) in Auckland, first as Safety Manager than then as Strategy and Network Development Manager. In these roles, Bill was part of the management team that overhauled the rail passenger operations in Auckland. Bill retired in early 2011 and returned to his home in Karori. After spending some time renovating the house, he became interested in local Karori issues. Subsequently he joined KRA as Infrastructure Coordinator and has spent a lot of time (with assistance from other members) on drainage, transport planning, and public transport matters. © Copyright Karori Residents’ Association – Author Bill Guest 10 September 2020 1 EMBARGOED AGAINST ANY DELIVERY UNTIL 11am 24 NOVEMBER 2020 KARORI TUNNEL IS UNFIT FOR PURPOSE When Karori Tunnel opened in 1900, the population the valley was around 1100. The tunnel’s main purpose was to encourage the expansion of housing, which was in short supply in Wellington. By 1954, when Karori’s population was 9,000, there were doubts about the capacity of the tunnel. Nothing was done. In 1962, when the population was 10,000 the issue arose again. Consultants were engaged, but again nothing was done. In 1972 Council decided to postpone any work indefinitely. The population was around 12,000. In 2020, when the population of Karori alone is between 16,000 and 18,000, and the tunnel serves 25,000 western suburbs residents, it is time to re-visit the issue and this time, take action. © Copyright Karori Residents’ Association – Author Bill Guest 10 September 2020 2 EMBARGOED AGAINST ANY DELIVERY UNTIL 11am 24 NOVEMBER 2020 Introduction Karori Tunnel and its approach roads are not satisfying the transport needs of Karori, Northland, Wilton, and Makara. The main problems are: 1. The tunnel is undersized and cannot take large vehicles. Double deck buses will not be possible through the tunnel as it is. Even the present single deck buses have difficulty without infringing over the centreline. 2. One lane in each direction is inadequate for traffic flows during much of the day, but especially at peak hours during the working week. 3. There is no provision for cyclists, and the tunnel is a serious hazard to all cyclists. 4. The footpath (87-92cm wide) is quite inadequate for pedestrians. 5. Traffic to and from Kelburn and Thorndon are frequently delayed at the mini roundabout at the end of the Kelburn Viaduct. 6. The Chaytor Street/Curtis Street/Raroa Road intersections are poorly designed, unsafe for cyclists, and with no reasonable provision for pedestrians. This paper examines the tunnel and argues for the revival of a proposal first advanced nearly 70 years ago for a second tunnel. The Tunnel Now Let us begin by looking at the tunnel as it is now. Photograph Taken from the Western End 26 April 2020 During the Covid19 Lock Down. © Copyright Karori Residents’ Association – Author Bill Guest 10 September 2020 3 EMBARGOED AGAINST ANY DELIVERY UNTIL 11am 24 NOVEMBER 2020 The footpath takes up 120cm of the base width of the tunnel, but by the time a small kerb and the barrier wall are subtracted, the footpath is 92cm at the western end, reducing to 87cm at the eastern end. (The interior doors of houses are typically 75cm wide, and front doors 80-85cm.) It is difficult for pedestrians to pass each other. A single pushchair is around 50cm wide so passing pushchairs is impossible. The narrow footpath is a serious impediment to persons with physical disabilities. Obtaining an accurate dimensioned cross-section profile of the tunnel proved to be difficult. Two relatively old plans supplied to me were in imperial dimensions, and one of them was a draftsman’s nightmare and was impossible to re-draw without making assumptions. Historical documents tended to give only the height and the width at the base of the walls, when clearly the shape of the curves is essential to assess what sized vehicles can pass through. Eventually, using a mixture of photographs and various measurements, the curve below was deemed satisfactory for analysis: Adding some details (next page): © Copyright Karori Residents’ Association – Author Bill Guest 10 September 2020 4 EMBARGOED AGAINST ANY DELIVERY UNTIL 11am 24 NOVEMBER 2020 Explaining: 1. A 30cm safety clearance is marked in orange to allow for driver error and vehicle swaying. (It is not important at the lower levels of the tunnel, or by the footpath.) 2. The centre line of the roadway is shown, displaced to the right of the tunnel centreline because of the footpath. 3. The maximum vehicle heights and widths of 4300mm and 2500mm are drawn in, but truncated where they infringe the safety margin. The vehicle envelopes have an infill of an Escher pattern (whimsically chosen to represent transport planning in Wellington) and coloured lime green (because our new buses are about that colour). 4. A centre safety gap of 600mm was allowed between the vehicle envelopes because they could contain moving vehicles, leaving approximately 300mm at the sides to the static wall and footpath barrier. These are extremely poor safety gaps even for an urban area. The problems with the tunnel size now become apparent. A full-size bus or truck might be able to travel from west to east if precisely placed and close to the centre line. There is no chance whatsoever of getting a full- sized bus or track to travel safely from east to west except by straddling the centre line. Further, there is no safety margin for cyclists on either side or in the middle. © Copyright Karori Residents’ Association – Author Bill Guest 10 September 2020 5 EMBARGOED AGAINST ANY DELIVERY UNTIL 11am 24 NOVEMBER 2020 It will come as no surprise that some truck-drivers have tried: © Copyright Karori Residents’ Association – Author Bill Guest 10 September 2020 6 EMBARGOED AGAINST ANY DELIVERY UNTIL 11am 24 NOVEMBER 2020 How Many People Does Karori Tunnel Serve? Using data found on the Wellington City Council web site, it was found that the population of the Onslow- Western Suburbs ward was a little over 45,000 people. The ward is shown as containing several discrete areas, with a population given for each area. After deducting those areas which would clearly use Ngauranga Gorge, Ngaio Gorge, Garden Road, or Raroa Road to reach the city, KRA reached the conclusion that about 25,000 people rely significantly on Karori Tunnel for transport to the CBD. This was an empirical exercise which required some assumptions and was repeated several times with variations to the assumptions being tested. The result seemed reasonably stable at 25,000 across all reasonable assumptions. Karori Tunnel is not only for Karori. It is also used by Makara, Creswick Valley, Wilton, Northland, and Otari residents. The Capacity of Karori Tunnel Suppose in a single lane of a road there is a string of vehicles with 20 metres between the noses of each vehicle, and moving at 30 km/hr. A few calculations show that the number of vehicles passing any point is 1496 per hour. While this is a simplistic scenario, it is a starting point for assessing the traffic capacity of Karori Tunnel, and it is not far off the actual situation at peak hours. Traffic engineers use more complex mathematics to introduce some statistical variability into the traffic flow, but methods used by NZTA and the US Federal Highway Administration give similar results for single lane capacity in urban areas. In 2016, Wellington City commissioned AECOM consultants to undertake a review of the potential impacts of increasing medium density housing in Karori on the traffic corridor to and from the central business district of Wellington. KRA is critical of some of the methodology described in the report, but there is some data that is revealing. (More on the methodology later). Table 1 of the AECOM report gives the number of vehicles travelling “through the Chaytor Street corridor” as 1795 in 2012, 1810 in 2013, 1660 in 2014, and 1746 in 2015. Sloppily, the paragraph before Table 1 states “Table 1 displays the volume of cars, buses, taxis, and cyclists at the Chaytor Street bus lane travelling through the corridor over the 2.5-hour morning peak period”. There are several problems with this statement: 1. It must be inferred by looking at other parts of the report that the totals are vehicles per hour during the morning peak period, and not the total for the 2.5-hour peak period. 2. Chaytor Street runs from the top of Glenmore Street through the tunnel, and up to the intersection with Karori Road outside the Karori Fire Station. There are bus lanes in both directions, with eastbound one stretching most of the way from Karori Road to the bus stop outside the tunnel, opposite the Birdwood Street intersection. So exactly where did the vehicle count for Table 1 take place? Elsewhere in the report much is made of the Karori Road section “east of Flers Street”.